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We have characterized complexes of the guide faunal groups (small-shelled fauna, archaeocyathids, trilobites, and brachiopods) and followed their stratigraphic and lateral distribution in the Cambrian deposits of the northern Siberian platform. Eleven boundaries, where these complexes undergo major biotic transformations, have been established. The boundaries are compared with those characterized in other studies, as well as with the carbon isotope dating from different sections of the Siberian Platform. Some of the boundaries established in this study correlate well with global biotic events and with the extrema of carbon isotope ratio curves. The examples include Boundary 1, the lower boundary of the Tommotian stage; Boundary 3, the lower boundary of the Atdabanian stage; Boundary 5, the lower boundary of the Botomian stage; and Boundaries 7 and 8 marking the transition from the Lower to Middle Cambrian in the Siberian Platform. Additionally, Boundary 9 is an almost universally present lower boundary of the Triplagnostus gibbus Zone of the Amgan stage.

Data on the stratigraphy of siliceous-basalt deposits of Ordovician age from Central Kazakhstan have been summarized. The age, succession, and correlation between these deposits are refined. Geological dating and correlation are based chiefly on conodonts and, to a lesser extent, graptolites. It is established that the age of these formations in the west and east of Central Kazakhstan is constrained by the Early to Middle Ordovician and in the interior structures (Zhungaria-Balkhash zone) it spans the entire Ordovician and, possibly, early Silurian. The siliceous and siliceous-terrigene deposits of Ordovician age are the water-deepest hemipelagic and pelagic sediments, and their accumulation corresponds to the maximum of Arenigian-to-Llanvirnian transgression. The reported paleo-geographic and paleotectonic data are in agreement with the existing paleotectonic reconstructions according to which Central Kazakhstan was a marginal basin of the West Pacific type during the Ordovician.

The paper addresses a comparative geochemical study of volcanic complexes that evolved in the Asia/Pacific transition zone from the Late Cenonian to Present.
Chemical compositions were analyzed in 111 representative samples of Cenozoic rocks from the eastern side of the Valaga Ridge (Eastern Kamchatka) on continuation of the Emperor's Ridge axis, in the region of hotspot volcanism; the dataset also includes 39 additional precise analyses published earlier by Puzankov et al. Trace elements were determined by INAA, XRF, AAS, LL methods and gamma spectrometry developed in UIGGM, Novosibirsk.
The magmatic complexes of Eastern Kamchatka and the surrounding regions were interpreted on the basis of rock chemistry as formed in spreading, island-arc, and transitional geodynamic environments. Broad occurrence of transitional igneous complexes brings together the Meso-Cenozoic volcanic system including magmatic chambers at different depths. Accretion postdates the magmatic evolution. According to paleontological and K-Ar age constraints, the Eastern Kamchatka hotspot has not moved much for 40 Ma (from the Eocene to the Pleistocene), though the total extent of alkaline and subalkaline rocks attains 200-300 km.

The paper presents results of Ar and He isotopic studies in rocks and sulphide ores of the Late Precambrian Dovyra dunite-troctolite layered intrusion (Northern Baikal region). The intrusion shows ³He/⁴He and ⁴⁰Ar/³⁶Ar ratios similar to other basic intrusions in the continental crust, and the gases in fluid inclusions contain a significant crystal component. The lowest ³He/⁴He and ⁴⁰Ar/³⁶Ar ratios, similar to those typical of fluids in the continental crust, were found in sulphide ores of the intrusion, which indicates involvement of crystal fluids in magmatic mineralization of the intrusion.

Analysis of borehole testing data shows that the large areas where reservoir rocks exist within the Bathonian permeable complex gravitate to certain structural features. These features have been analyzed with respect to inflow of hydrocarbons. According to petroleum potential, the structural settings were classified as highly promising, promising, and nonpromising.

Geodetic surveys, especially repeated levelling carried out for the first time in the territory of the Altai-Sayan province through the recent decades, have yielded a cartographic model of ongoing vertical movements of the Earth's surface. The numerical parameters of the model were obtained from the equation of levelling network consisting of closed polygons and isolated lines, about 10,000 km of total length.
The model reflects regional-scale regular distribution of the rates of vertical movements. According to this regularity, the Biya-Katun', Barnaul, and Mras blocks are stable, while the background ongoing vertical movements in the province are regional-scale doming south of the Barnaul-Biya-Katun' stable block and subsidence of the province's north-western part north of the stable zone. Doming is accompanied by local but often considerable subsidence which provides further deepening of intermountain depressions.
Analysis of the relationship between active and neotectonic structures revealed regions in which the ongoing movements are conformal to the evolution trends of the earlier neotectonic stage and those in which they are different. The obtained model of ongoing vertical movements of the Earth's surface was also used to detect zones of active faulting.

The Riphean (1500-1450 to 1000-950 Ma, from ⁴⁰Ar/³⁹Ar and K/Ar age methods) section of petroliferous peritidal carbonates in the Baikit uplift in the western Siberian Platform contains five sequences, each divided into three to five subsequences, distinguished on the basis of sediment logy and isotope geochemistry. The five sequences deposited in the period from 80 to 100 Ma and reflect major fluctuations of the sea level. The stability of 13C estimates is confirmed by petro-graphical, geochemical, and isotope data (over 350 analyses), which show that early diagenic dolomites may retain primary ¹³C signal subject to only slight changes. The ¹³C values in the lowermost carbonates (1450-1350 Ma, from isotope data) are about zero (-0.2 to 0.5). The overlying section contains long intervals with low positive d¹³C values of 0.5 to 2.0, occasionally up to 3.0, alternating with shorter intervals dominated by negative ¹³C values (to 2.2). The negative shifts correspond to the deposition of lower Yurubchen (~1350 Ma), upper Yurubchen-Dolgokta (1270-250 Ma), Kopcher (1100-1080 Ma), and upper Yukta-lower Tokur (about 1000 Ma) subsequences. The main trends in the sea level fluctuations correlate well with ¹³C variations: The negative isotopic shifts coincide with the boundaries of the five major sequences; the intervals with medium positive ¹³C record high sea stand and correspond to the periods of carbonate shelf aggradation; low ¹³C values often correlate with the boundaries and the lower segments of the subsequences. Isotope and geological data from other regions indicate that the low sea stand periods correlated with the boundaries of the sedimentary subsequences in the Baikit uplift are most likely associated with global geological events and reflect eustatic fluctuations.

Lithological and geochemical interpretation of standard log data for the Bazhenov Formation (southeastern and central West Siberian Plate), their classification and 1:500,000 mapping show an argillaceous-siliceous-sapropelic composition and high organic matter (colloalginite) content of the highly resistive and gamma-active parts of the sections. The Bazhenov deposition was controlled, among other factors, by the bottom topography and the depth of the ocean which transgressed to the south-eastern West Siberian Plate in its early and, especially, intermediate evolution stages. The distribution of rock groups reflected in depth-dependent variations in apparent resistivity made a basis for distinguishing different types and classes of sections within the formation, including those promising for oil and gas.

Three conceptual fundamentals are proposed as a base for estimation of HC resources and simultaneously for analysis and planning of prospecting surveys. The first is the qualitative dynamic approach to recognition of objects for prediction of petroleum potential (reservoirs, cap rocks, traps, trapping areas, and volumes). The second is adaptive support for the oil-geological model of the region to be estimated on the basis of logged information technologies. The third is continuous refinement of HC balance of all kinds on the basis of constant comparison of current local estimates with current results of prospecting surveys. A method of geometrical parameterization is proposed for the Neocomian West Siberian clino-forms. Some implications of the proposed approach are discussed.

Petrological, geochemical, and isotope (U-Pb, Sm-Nd, Sr-Sr, and Ar-Ar) studies of the Yeruda and Chirimba granitoids show that they belong to different magmatic complexes. The Yeruda low-Kcalc-alkalic granitoids (8781.5 Ma, U-Pb dating from zircon) have a geochemistry corresponding to intermediate I-S-type granites. Their primary melts may have been derived from island-arc complexes, strongly contaminated with the material of old continental crust, which were molten as a result of a collision about 880 Ma ago. The Chirimba high-K and high-F subalkalic granitoids (7618 Ma, U-Pb dating from zircon) apparently formed by melting of Early Proterozoic (Sm-Nd model age) crustal substrate, including the lower crustal material. In geochemistry and isotope composition they are similar to A-type granites that formed in postcollisional or within-plate environments. The Chirimba granitoids are 120 Ma younger than the Yeruda rocks and thus cannot have been caused by the same event. Therefore, the region of the Yenisei Range may have experienced repeated accretionary and collisional events in Late Proterozoic time.